Immunotherapeutic strategies for breast cancer

描述(申请人提供)：我们建议开发单核细胞增多性李斯特氏菌，作为治疗HER-2/neu表达的乳腺肿瘤的癌症药物。我们已经证明，分泌肿瘤特异性抗原的重组单核细胞增多性乳杆菌不仅可以保护肿瘤免受攻击，而且在移植到正常同基因小鼠体内后，还可以诱导肉眼已建立的肿瘤消退。这种令人印象深刻的抗肿瘤反应可能是由于这种兼性细胞内细菌逃脱吞噬小体并在细胞质中生存和生长的不同寻常的能力。因此，单核细胞增多性李斯特氏菌分泌的抗原非常有效地靶向于第II类和第I类限制性的抗原呈递途径。因此，这种细菌可能是理想的疫苗载体，以增强细胞对肿瘤特异性抗原的免疫反应，作为一种治疗癌症的方法。为了确定如何优化单核细胞增多性乳杆菌作为人类癌症疫苗的使用，我们将使用FVB背景下的HER-2/neu转基因乳腺癌小鼠模型来测试单核细胞增多性乳杆菌克服对自发产生的肿瘤的耐受性的能力。自从第一次提交这项资助以来，我们已经完成了进行这些实验所需的LM载体的构建，包括五个分泌HER-2蛋白过度表达片段的LM-LLO-HER-2/neu菌株，并发现当将它们传递给正常和HER-2/neu转基因FVB小鼠时，它们似乎揭示了HER-2/neu中的隐蔽表位。我们已经证实，这些表位是通过将抗原与LLO融合并由单核细胞增多性乳杆菌递送来揭示的，而不是通过将HER-2/neu作为蛋白质片段递送来揭示的。因此，本提议的一个新的子目标(特定目标1c)是完全映射这些表位，以便我们可以在特定目标2中测量它们在整体免疫反应中的贡献。最后，在特定的目标3中，我们将比较李斯特菌HER-2/neu疫苗对HER-2/neu转基因小鼠移植和自发生长的乳腺肿瘤的影响。自上次提交以来，我们发现五个LM-LLO-HER-2/neu片段载体对HER-2/neu转基因小鼠的自发性肿瘤生长具有不同的影响能力，但对可移植肿瘤的影响相似，并为探索这一发现背后的机制增加了新的目标。

DESCRIPTION (provided by applicant): We propose to develop Listeria monocytogenes, as a cancer therapeutic for HER-2/neu expressing breast tumors. We have shown that recombinant L. monocytogenes that secretes a tumor specific antigen can not only protect against tumor challenge but can also induce regression of macroscopic established tumors after transplantation into normal syngeneic mice. This impressive anti-tumor response is probably due to the unusual ability of this facultative intracellular bacterium to escape the phagolysosome and live and grow in the cytoplasm of cells. Antigens secreted by L. monocytogenes, therefore, are very effectively targeted to both the class II and class I restricted pathways for antigen presentation. Thus this bacterium may be the ideal vaccine vector for boosting the cell mediated immune response to tumor specific antigens as a cancer therapeutic. To determine how to optimize the use of L. monocytogenes as a cancer vaccine in humans we will use a HER-2/neu transgenic mouse model of breast cancer on the FVB background to test the ability of L. monocytogenes to overcome tolerance to spontaneously arising tumors. Since the first submission of this grant we have completed the construction of Lm vectors rquired to perform these experiments, including five Lm-LLO-Her-2/neu strains that secrete overalpping fragments of the HER-2 protein and discovered that they appear to reveal cryptic epitopes in HER-2/neu when delivered to the normal and HER-2/neu transgenic FVB mouse. We have verified that these epitopes are revealed by fusing the antigen to LLO and delivery by L. monocytogenes and not by delivering HER-2/neu as protein fragments.Thus a new sub- aim of this proposal (Specific Aim 1c) is to fully map these epitopes so that we can measure their contribution to the overall immune response in Specific Aim 2. The goal of Specific Aim 2 is to correlate the anti-tumor effectiveness of the Lm-LLO-HER-2/neu recombinants with the induction of B and T cell immunity. Finally, in Specific Aim 3, we will compare the efficacy of the Listeria HER-2/neu vaccines to impact on transplanted and spontaneously arising breast tumors in mice transgenic for HER-2/neu. Since the last submission we have found that the five Lm-LLO-Her-2/neu fragment vectors have different abilities to impact on sponataneous tumor growth but have similar impacts on the tranplantable tumor in the HER-2/neu trangenic mouse and have added new aims that explore the mechanism behind this finding.